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6 records – page 1 of 1.

Dibenzofurans and Pseudodepsidones from the Lichen Stereocaulon paschale Collected in Northern Quebec.

https://arctichealth.org/en/permalink/ahliterature279041
Source
J Nat Prod. 2017 Jan 12;
Publication Type
Article
Date
Jan-12-2017
Author
Claudia Carpentier
Emerson Ferreira Queiroz
Laurence Marcourt
Jean-Luc Wolfender
Jabrane Azelmat
Daniel Grenier
Stéphane Boudreau
Normand Voyer
Source
J Nat Prod. 2017 Jan 12;
Date
Jan-12-2017
Language
English
Publication Type
Article
Abstract
Chemical investigation of the methanol extract of the lichen Stereocaulon paschale collected in Nunavik, Canada, led to the isolation and identification of two new dibenzofurans (1 and 3) and 11 known lichen metabolites. The structures of the new compounds were established by analysis of 1D and 2D NMR spectroscopic and high-resolution mass spectrometric data. Herein, the first isolation of ascomatic acid dibenzofuran derivatives (1-3) from a whole lichen organism is reported. In addition, some of the isolated metabolites showed antibacterial activity against the oral pathogens Porphyromonas gingivalis and Streptococcus mutans.
PubMed ID
28079378 View in PubMed
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Different parts, different stories: climate sensitivity of growth is stronger in root collars versus stems in tundra shrubs.

https://arctichealth.org/en/permalink/ahliterature279563
Source
Glob Chang Biol. 2017 Jan 20;
Publication Type
Article
Date
Jan-20-2017
Author
Pascale Ropars
Sandra Angers-Blondin
Marianne Gagnon
Isla H Myers-Smith
Esther Lévesque
Stéphane Boudreau
Source
Glob Chang Biol. 2017 Jan 20;
Date
Jan-20-2017
Language
English
Publication Type
Article
Abstract
Shrub densification has been widely reported across the circumpolar arctic and subarctic biomes in recent years. Long-term analyses based on dendrochronological techniques applied to shrubs have linked this phenomenon to climate change. However, the multi-stemmed structure of shrubs makes them difficult to sample and therefore leads to non-uniform sampling protocols among shrub ecologists, who will favor either root collars or stems to conduct dendrochronological analyses. Through a comparative study of the use of root collars and stems of Betula glandulosa, a common North American shrub species, we evaluated the relative sensitivity of each plant part to climate variables, and assessed if this sensitivity is consistent across three different types of environments in northwestern Québec, Canada (terrace, hilltop and snowbed). We found that root collars had greater sensitivity to climate than stems, and that these differences were maintained across the three types of environment. Growth at the root collar was best explained by spring precipitation and summer temperature, whereas stem growth showed weak and inconsistent responses to climate variables. Moreover, sensitivity to climate was not consistent among plant parts, as individuals having climate sensitive root collars did not tend to have climate sensitive stems. These differences in sensitivity of shrub parts to climate highlight the complexity of resource allocation in multi-stemmed plants. Whereas stem initiation and growth are driven by micro-environmental variables such as light availability and competition, root collars integrate the growth of all plant parts instead, rendering them less affected by mechanisms such as competition and more responsive to signals of global change. Although further investigations are required to determine the degree to which these findings are generalizable across the tundra biome, our results indicate that consistency and caution in the choice of plant parts are a key consideration for the success of future dendroclimatological studies on shrubs. This article is protected by copyright. All rights reserved.
PubMed ID
28107770 View in PubMed
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Divergence of Arctic shrub growth associated with sea ice decline.

https://arctichealth.org/en/permalink/ahliterature303904
Source
Proc Natl Acad Sci U S A. 2020 12 29; 117(52):33334-33344
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Date
12-29-2020
Author
Agata Buchwal
Patrick F Sullivan
Marc Macias-Fauria
Eric Post
Isla H Myers-Smith
Julienne C Stroeve
Daan Blok
Ken D Tape
Bruce C Forbes
Pascale Ropars
Esther Lévesque
Bo Elberling
Sandra Angers-Blondin
Joseph S Boyle
Stéphane Boudreau
Noémie Boulanger-Lapointe
Cassandra Gamm
Martin Hallinger
Grzegorz Rachlewicz
Amanda Young
Pentti Zetterberg
Jeffrey M Welker
Author Affiliation
Institute of Geoecology and Geoinformation, Adam Mickiewicz University, 61-680 Poznan, Poland; kamzik@amu.edu.pl.
Source
Proc Natl Acad Sci U S A. 2020 12 29; 117(52):33334-33344
Date
12-29-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Keywords
Arctic Regions
Climate
Humidity
Ice Cover
Models, Theoretical
Plant Development
Seasons
Soil
Temperature
Abstract
Arctic sea ice extent (SIE) is declining at an accelerating rate with a wide range of ecological consequences. However, determining sea ice effects on tundra vegetation remains a challenge. In this study, we examined the universality or lack thereof in tundra shrub growth responses to changes in SIE and summer climate across the Pan-Arctic, taking advantage of 23 tundra shrub-ring chronologies from 19 widely distributed sites (56°N to 83°N). We show a clear divergence in shrub growth responses to SIE that began in the mid-1990s, with 39% of the chronologies showing declines and 57% showing increases in radial growth (decreasers and increasers, respectively). Structural equation models revealed that declining SIE was associated with rising air temperature and precipitation for increasers and with increasingly dry conditions for decreasers. Decreasers tended to be from areas of the Arctic with lower summer precipitation and their growth decline was related to decreases in the standardized precipitation evapotranspiration index. Our findings suggest that moisture limitation, associated with declining SIE, might inhibit the positive effects of warming on shrub growth over a considerable part of the terrestrial Arctic, thereby complicating predictions of vegetation change and future tundra productivity.
PubMed ID
33318214 View in PubMed
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Is subarctic forest advance able to keep pace with climate change?

https://arctichealth.org/en/permalink/ahliterature306272
Source
Glob Chang Biol. 2020 07; 26(7):3965-3977
Publication Type
Journal Article
Date
07-2020
Author
W Gareth Rees
Annika Hofgaard
Stéphane Boudreau
David M Cairns
Karen Harper
Steven Mamet
Ingrid Mathisen
Zuzanna Swirad
Olga Tutubalina
Author Affiliation
Scott Polar Research Institute, University of Cambridge, Cambridge, UK.
Source
Glob Chang Biol. 2020 07; 26(7):3965-3977
Date
07-2020
Language
English
Publication Type
Journal Article
Keywords
Alaska
Arctic Regions
Canada
Climate change
Forests
Siberia
Tundra
Abstract
Recent climate warming and scenarios for further warming have led to expectations of rapid movement of ecological boundaries. Here we focus on the circumarctic forest-tundra ecotone (FTE), which represents an important bioclimatic zone with feedbacks from forest advance and corresponding tundra disappearance (up to 50% loss predicted this century) driving widespread ecological and climatic changes. We address FTE advance and climate history relations over the 20th century, using FTE response data from 151 sites across the circumarctic area and site-specific climate data. Specifically, we investigate spatial uniformity of FTE advance, statistical associations with 20th century climate trends, and whether advance rates match climate change velocities (CCVs). Study sites diverged into four regions (Eastern Canada; Central and Western Canada and Alaska; Siberia; and Western Eurasia) based on their climate history, although all were characterized by similar qualitative patterns of behaviour (with about half of the sites showing advancing behaviour). The main associations between climate trend variables and behaviour indicate the importance of precipitation rather than temperature for both qualitative and quantitative behaviours, and the importance of non-growing season as well as growing season months. Poleward latitudinal advance rates differed significantly among regions, being smallest in Eastern Canada (~10 m/year) and largest in Western Eurasia (~100 m/year). These rates were 1-2 orders of magnitude smaller than expected if vegetation distribution remained in equilibrium with climate. The many biotic and abiotic factors influencing FTE behaviour make poleward advance rates matching predicted 21st century CCVs (~103 -104  m/year) unlikely. The lack of empirical evidence for swift forest relocation and the discrepancy between CCV and FTE response contradict equilibrium model-based assumptions and warrant caution when assessing global-change-related biotic and abiotic implications, including land-atmosphere feedbacks and carbon sequestration.
PubMed ID
32281711 View in PubMed
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Long-term interactions between migratory caribou, wildfires and Nunavik hunters inferred from tree rings.

https://arctichealth.org/en/permalink/ahliterature6650
Source
Ambio. 2004 Dec;33(8):482-6
Publication Type
Article
Date
Dec-2004
Author
Serge Payette
Stéphane Boudreau
Claude Morneau
Nadia Pitre
Author Affiliation
Université Laval, Québec City, Canada. serge.payette@bio.ulaval.ca
Source
Ambio. 2004 Dec;33(8):482-6
Date
Dec-2004
Language
English
Publication Type
Article
Keywords
Animal Population Groups
Animals
Ecosystem
Environment
Fires - history - statistics & numerical data
History, 19th Century
History, 20th Century
Humans
Inuits - history - statistics & numerical data
Meat
Plant Components
Population Dynamics
Quebec
Reindeer
Research Support, Non-U.S. Gov't
Seasons
Trees
Abstract
Barren-ground caribou (Rangifer tarandus) herds in North America may reach considerable size and undertake large-scale seasonal migrations from the Arctic tundra to the boreal forest. To test the caribou decline hypothesis associated with native harvesting and fire, we have documented the long-term trends of caribou activity based on a novel approach which uses tree-ring dated trampling scars produced by caribou hooves in the extensive trails distributed over the summer and winter ranges of the Rivièreaux-Feuilles herd (RAF herd, east of Hudson Bay in northern Quebec). The age structure data of trampling scars from lichen woodlands distributed over the entire RAF range confirmed the overall trends of caribou activity from the late 1700s to present time. Over the last 200 years, the RAF herd has undergone two highs in the late 1700s and 1900s separated by a moderate activity pattern in the late 1800s. Native harvesting was possibly involved in the early 1900s decline, although at a moderate level. The reduced magnitude of caribou activity during this period has not modified the natural cycle of highs and lows, which suggests that other demographic factors were controlling the changing caribou abundance. Our data also show that only exceptionally large fires may have a minor, short-lived impact on caribou migrations but not on caribou numbers.
PubMed ID
15666677 View in PubMed
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Re-activation of landslide in sub-Arctic areas due to extreme rainfall and discharge events (the mouth of the Great Whale River, Nunavik, Canada).

https://arctichealth.org/en/permalink/ahliterature305130
Source
Sci Total Environ. 2020 Nov 20; 744:140991
Publication Type
Journal Article
Date
Nov-20-2020
Author
Piotr Owczarek
Magdalena Opala-Owczarek
Stéphane Boudreau
Patrick Lajeunesse
Lukasz Stachnik
Author Affiliation
Institute of Geography and Regional Development, University of Wroclaw, Pl. Uniwersytecki 1, 50-138 Wroclaw, Poland. Electronic address: piotr.owczarek@uwr.edu.pl.
Source
Sci Total Environ. 2020 Nov 20; 744:140991
Date
Nov-20-2020
Language
English
Publication Type
Journal Article
Abstract
Climate change is impacting surficial geomorphic processes, especially in sensitive areas such as the sub-Arctic. One of the most common examples involves landslides, which often develop in glacio-isostatically raised marine clays in northeastern Canada. One of these sites, an expansive area of complex landslide terrain located at the mouth of the Great Whale River in Nunavik, has already been studied due to its age and morphology. We present new data, based on the multidisciplinary research including geomorphic, dendrochronological, and hydroclimatological analyses, allowing us to determine how contemporary climate change has affected landslide reactivation during the last 80 years. Our research included collecting 60 cores from Picea glauca trees, growing on the marginal zone of a landslide deposit, as well as from a reference site. The tilted trees formed eccentric growth-ring patterns, which provided us with reliable dates on the landslide events. In addition to these dendrochronological data, we studied these landslides using repeated aerial photography, which showed changes in river channel constrictions in the period 1969-2019. Based on the eccentricity index of the tree ring data, we recognized disturbance events due to landslides. We compared these data with the hydroclimatological conditions and found clearly visible correlations between heavy rainfall and discharge (>95th percentile) of the Great Whale River. The increased landslide activity over the past several years can be linked to an increase in extreme summertime rainfall events. Increased landslide activity poses a real threat, through its input of large amounts of fine-grained sediment to the river, causing it to narrow.
PubMed ID
32755789 View in PubMed
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6 records – page 1 of 1.